<242 ON THE GLASSES OF THE 



indeed to be indispensably necessary to the geologist. 

 And no doubt the testaceous covering of an animal is al- 

 ways so intimately connected with its structure that it 

 would be unpardonable in the naturalist, who ought to 

 leave nothing without investigation, to forget shells. But, 

 on the other hand, when we call to our recollection the 

 lamentable error committed by Linnaeus and his disci- 

 ples in not following the example of our celebrated Lister 

 in the arrangement of the Mollusca, we become con- 

 vinced that there was about as much hope of their ever 

 arriving at the truth by the means they chose to adopt, as 

 that a collection of the wings of different insects should 

 ever instruct us fully in the natural history of the several 

 animals to which they belong. It is said that Klein formed 

 an ornithological cabinet, in which the feet and beaks of 

 birds were only to be seen, because, according to his 

 notions, these were all the parts requisite for the proper 

 arrangement of the feathered creation. He thought that 

 it was possible to be a good ornithologist without knowing 

 the least of a bird but its beak and claw. We may indeed 

 laugh at this ; but at the same time we ought to inquire 

 whether similar ridicule may not with justice be extended 

 to those conchologists who, having procured a shell, de- 

 scribe and classify it without deigning to bestow a single 

 thought on the nature of the poor animal which con- 

 structed it for its habitation. A curious arrangement, as 

 might have been expected, has come of this method of pro- 

 ceeding ; for we have Annulose animals united to true 

 Mollusca, merely because they have shells, and true Mol- 

 lusca separated from this division, merely because they 

 have no shells. In some cases even, as in the genus Limax, 

 it is sufficient for the shell to be small in order to set it 



